Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?geqp3

Computes the QR factorization of a general m-by-n matrix with column pivoting using level 3 BLAS.

Syntax

call sgeqp3
(
m
,
n
,
a
,
lda
,
jpvt
,
tau
,
work
,
lwork
,
info
)
call dgeqp3
(
m
,
n
,
a
,
lda
,
jpvt
,
tau
,
work
,
lwork
,
info
)
call cgeqp3
(
m
,
n
,
a
,
lda
,
jpvt
,
tau
,
work
,
lwork
,
rwork
,
info
)
call zgeqp3
(
m
,
n
,
a
,
lda
,
jpvt
,
tau
,
work
,
lwork
,
rwork
,
info
)
call geqp3
(
a
,
jpvt
[
,
tau
]
[
,
info
]
)
Include Files
  • mkl.fi
    ,
    lapack.f90
Description
The routine forms the
QR
factorization of a general
m
-by-
n
matrix
A
with column pivoting:
A*P
=
Q*R
(see Orthogonal Factorizations ) using Level 3 BLAS. Here
P
denotes an
n
-by-
n
permutation matrix. Use this routine instead of geqpf for better performance.
The routine does not form the matrix
Q
explicitly. Instead,
Q
is represented as a product of min(
m
,
n
) elementary reflectors . Routines are provided to work with
Q
in this representation.
Input Parameters
m
INTEGER
.
The number of rows in the matrix
A
(
m
0
).
n
INTEGER
.
The number of columns in
A
(
n
0
).
a
,
work
REAL
for
sgeqp3
DOUBLE PRECISION
for
dgeqp3
COMPLEX
for
cgeqp3
DOUBLE COMPLEX
for
zgeqp3
.
Arrays:
a
(
lda
,*) contains the matrix
A
.
The second dimension of
a
must be at least max(1,
n
).
work
is a workspace array, its dimension
max(1,
lwork
)
.